class_docstr: Canonicalizes break statements into additional conditionals.
class_docstr_tok: ["Canonicalizes","break","statements","into","additional","conditionals","."]
docstr: Prevents the block from executing if var_name is set.
docstr_tok: ["Prevents","the","block","from","executing","if","var_name","is","set","."]
code: def _guard_if_present(self, block, var_name):
      """Prevents the block from executing if var_name is set."""
      if not block:
          return block
  
      template = """
          if not var_name:
            block
        """
      node = templates.replace(template, var_name=var_name, block=block)
      return node
  
file_path: tensorflow/tensorflow/python/autograph/converters/break_statements.py
imports: from tensorflow.python.autograph.core import converter
  from tensorflow.python.autograph.pyct import anno
  from tensorflow.python.autograph.pyct import qual_names
  from tensorflow.python.autograph.pyct import templates
  from tensorflow.python.autograph.pyct.static_analysis import activity
  from tensorflow.python.autograph.pyct.static_analysis.annos import NodeAnno
label_desc: Use image node_id 2 for calling the BreakTransformer obj's underlying member method code with example usage: obj._guard_if_present(block, var_name) and returns: node, block